a lot - two words! Arrrrgggghhhh!!!
The setup that BDK's running is straight off Trophy Truck rear suspension designs. His will just be a bit smaller
The shock mounts below the line between the two ends of the upper link, therefore there is no twisting motion of the upper link, other than some that the shock will input. It's an extremely strong, very well proven and reliable setup.
What you see in the pick that he posted is a very technical, and unobtainable upper link. There's a lot of secret squirrel stuff going on that he's not showing yet.
(yea, right...)
If you go find BDK's build, you'll see some of the laser cut parts that will make up the upper link.